Back in January, the musicians’ collective known as the Brooklyn Jazz Underground marked its first anniversary with a three-day festival of performances by several members. Its second compilation culls tracks from albums by 10 of them. The overall effect recalls the Live From the Knitting Factory compilations from the early ’90s that turned many college-radio geeks on to progressives like Curlew, Marilyn Crispell and Sonny Sharrock. Like those collections, there is no unifying sound here, and therein lies the appeal. Drummer Sunny Jain’s group combines Middle Eastern vocals with jazz licks. In Shane Endsley’s “Song 4” his trumpet and Ben Wendell’s tenor saxophone are multitracked and electrified as they play a jagged melody over a Rhodes-driven rhythm section. At the other end of the spectrum is Anne Mette Iversen’s “South,” which deftly combines a piano trio with string quartet and soprano sax. At least one of these tracks comes from an album that’s nearly a year old at this point. But with the number of artists releasing CDs on a regular basis, making it harder to discover new musicians via impulse buying, Brooklyn Jazz Underground Volume 2 is a significant purchase for the discoveries it offers and for the support it provides for its namesake.